package test2;

public class demo {

	public static void main(String[] args) {
		System.out.println(f(20));
	}

	
	//阶乘的算法
	public static int f(int n) {
		if (n==1) {
			return 1;
		}else {
			return n*f(n-1);
		}
		
		
	}


}
